Electronic circuitry often must use and store sensitive information such as financial data, account numbers, passwords, personal identification numbers (PIN), access codes, encryption keys, names, addresses, personal information, and other information that is not to fall into the hands of thieves and hackers. For example, credit card purchases are often made at retail stores using a device commonly referred to as a “point of sale” (POS) terminal. The POS terminal is typically coupled to a financial institution via an electronic communication link. A customer at the store may, for example, swipe a credit card through a credit card reader on the POS terminal to pay for merchandise. An encryption key stored in the POS terminal then encrypts information about the transaction including the credit card number and the amount of the transaction, and the encrypted information is communicated from the POS terminal to the financial information. If a thief can obtain access to the encryption key, or can obtain access to the sensitive information, then the thief may be able to make unauthorized purchases or otherwise steal money or use the customer's sensitive information in an unauthorized manner. The sensitive information must, however, generally be stored at least temporarily in circuitry within the POS terminal in order for the POS device to be able to perform its communication function.
To prevent a thief from breaking into a POS terminal and reading sensitive information out of the circuitry of the POS terminal, a mesh of very fine conductors is often employed. This fine mesh (referred to here as an “anti-tamper mesh”) is made to cover the circuitry that contains the sensitive information. If the thief were to probe the POS terminal circuitry or to take the POS terminal circuitry apart, then the thief's actions would likely cause conductors of the mesh either to be shorted together or to be severed. There are many variations of anti-tamper mesh structures known in the art. A tamper detect circuit within a volume protected by the mesh is coupled to the mesh and can detect the thief's tampering with the mesh. If a tamper condition occurs, then the tamper detect circuit causes the sensitive information stored in the POS terminal circuitry to be erased before the thief can gain physical access to the circuitry and read the information out of the circuitry.
There are many ways known in the art to protect a volume using an anti-tamper mesh. These ways are effective to different degrees, but generally these known ways of providing the anti-tamper mesh involve an undesirable amount of added cost and/or manufacturing complexity. Even if these ways are established ways that are adequate, it is nevertheless desirable to be able to add to the tamper proof nature of the POS terminal in a cost effective manner, even if the added protection may be slight.